I voted no, because Karen's fairly young. But from what I understand, it CAN be a gradual process. Or depend on genetics/family history. I'm voting we're too young...wait, did I say "we"?????
I'm 46 and for the last 5-6 years, I get hot flashes and nightsweats when I have PMS although I'm still getting my period regularly. It's a hormonal change gearing up for menopause. It's called perimenopause. If the woman in your family are early to menopause, Karen might be on the cusp of starting.